Method and mobile radio communication network for the transmission of packet data

ABSTRACT

The invention relates to a method for controlling the exchange of data between mobile subscribers in a packet-oriented mobile communication network, wherein management of each subscriber occurs at a specific control node (SGSN) of the mobile communication network according to the actual whereabouts of the subscriber inside the mobile communication network; links from/to a mobile communication transmitter device of the mobile subscriber are controlled inside the mobile communication network by the corresponding control node; wherein an address register comprising all of the addresses allocated to mobile subscribers managed by said control node is stored in the control network node; a destination address allocated to the data packets is read out in the control network node from incoming data packets and is compared to the address register by means of a search function; if the destination address is available in the address register, the data packets are exclusively handled by the control node in the mobile communication network and are further transmitted; if the destination address is missing in the address register, the data packets are transmitted by the control node to another network node (GGSN) of the mobile communication network for further processing.

The present invention relates to a method for a mobile radiotelecommunication network for transmitting packet data between twomobile communication terminals. In networks for mobile communication,there are a plurality of network elements which are involved in thetransmission of voice data, multimedia data or other useful data. Thepresent architecture of mobile radio communication networks which aresuitable for transmitting packet data, such as in GPRS and/or UMTSnetworks, is characterized, inter alia, in that there is a centralgateway, in the case of a GPRS network a “GGSN”, for example, whichensures a link to a packet data network, such as the Internet. Between amobile communication terminal and the central gateway, subscriber dataare tunneled in order to assist the mobility of the mobile communicationterminal. A particular spatial area, a “routing area”, has precisely oneassociated control network node, in the case of a GPRS network, an“SGSN”, which controls the mobility of a mobile communication terminal.As regards the design and handling of logical connections, such as PDPcontexts, the networks are optimized for “client/server” services. Inthe case of this type of communication, in principle, a plurality ofsubscribers or clients communicate from arbitrary locations, forexample, in the form of a star, with a central server which is matchedto the incumbent load. A further feature is the highly asymmetrictraffic characteristic. There is very little traffic from the subscriberor client to the server, whereas from the server to the subscriber thereis a comparatively large volume of traffic. A customary scenario in thiscase is, for example, data traffic between a mobile communicationterminal and a destination which is situated outside of the actualmobile radio telecommunication network, that is to say behind thecentral gateway, such as a host on the Internet or a WAP-GW.

Accordingly, mobile radio communication networks are not suitable forapplications which send data from a mobile communication terminal toanother mobile communication terminal. Such direct data transmissionfrom one user to another user is called a “peer-to-peer” or P2Ptransmission. At present, particularly on the Internet, more thanproportional growth in the volume of data is being recorded, however,particularly in the case of “P2P services”. One example which may becited is, by way of example, markets for music and video clips which arebased on direct data interchange between users.

As the scope of functions of mobile communication terminals, such asdigital cameras, MP3 players or multimedia cards, increases, a similaruser behavior can be expected for mobile users or “mobile subscribers”too. In contrast to simple text messages and ringtones, which can easilybe sent using a “short message service”, i.e. SMS, the volume of dataproduced as a result of sending audio and still-picture files or datastreams, for example, will increase exponentially in this case. From thepoint of view of a network operator, it is therefore becomingincreasingly attractive to route data in such a scenario as directly aspossible, thus saving costs.

It is therefore an object of the present invention to provide a bettersupport for “P2P services” in mobile radio communication networks,particularly in GPRS or UMTS networks, and to optimize the routing ofpacket data in situations which arise particularly frequently.

This object is achieved by a method as claimed in claim 1 and via mobilecommunication network as claimed in claim 4. Further preferredembodiments are illustrated in the subclaims.

Claim 1 provides a method for controlling data interchange betweenmobile subscribers in a packet-oriented mobile communication network,where

-   -   each subscriber is managed at a particular control network node        (SGSN) in the mobile communication network on the basis of his        respective current location in the mobile communication network,    -   connections from/to a mobile communication terminal associated        with the mobile subscriber are controlled within the mobile        communication network by the appropriate control network node,        in which    -   the control network node stores an address register containing        all of the addresses associated with the mobile subscribers        managed by the control network node,    -   the control network node takes incoming data packets and reads a        destination address associated with the data packets, and uses a        search function to compare said destination address with the        address register,    -   if the destination address is present in the address register        then the data packets are handled and forwarded within the        mobile communication network exclusively by the control network        node,    -   if the destination address is absent from the address register        then the data packets are routed from the control network node        to a further network node (GGSN) in the mobile communication        network for the purpose of further handling.

It is known, as already mentioned, that subscriber data packets passingthrough the mobile radio communication network transparently, that is tosay in tunneled fashion, do not become visible until behind the centralgateway, in the case of a GPRS network behind the GGSN, for example,i.e. behind the tunnel end point. From this central gateway, the datapackets are then transported to an appropriately indicated destinationaddress using conventional routing. From a first mobile communicationterminal, a data packet, for example, is tunneled via a control unit, inthe case of a UMTS network via a radio network controller (RNC), forexample, a control network node, such as an SGSN, to the centralgateway, such as a GGSN. At the central gateway node, the incoming datapacket is then unpacked or decapsulated and is then routed. If thedestination address is another second mobile communication terminal,then the data packet is routed to that central gateway node whichmanages a tunnel to the second mobile communication terminal. There, thedata packet is packed or encapsulated again and is finally tunneled viaa control network node, such as an SGSN, and a control unit, such as aradio network controller (RNC), to the destination address, i.e. to thesecond mobile communication terminal.

To date, it has been possible to interchange multimedia contents betweentwo mobile communication terminals using a “multimedia message” service(“MMS”), for example. This service has a “multimedia message” servicecenter (“MMSC”) which acts as a buffer store when applying the“store-and-forward” principle. In this service, the data packets whichare to be sent from one mobile communication terminal to another mobilecommunication terminal are generally routed via network nodes which areat a great physical distance, even if the mobile communication terminalsare situated at locations close to one another. The result isunnecessarily high latencies and unnecessary loading of the networkwhere it would otherwise be possible to transport additional packetdata.

One advantage of the present invention is now that if the mobilecommunication terminals interchanging data are situated at locationsclose to one another and are therefore managed by the same controlnetwork node, in the case of a GPRS network by the same SGSN, forexample, then the routing for these data packets is optimized. Thesearch function which the invention provides at the control network nodeidentifies relevant data packets, which are handled exclusively by thecontrol network node, such as the SGSN, by bypassing a further networknode, such as a GGSN in the case of a GPRS network. A significantproportion of the data traffic between two mobile communicationterminals is brought about by users who are physically close to oneanother, such as when ringtones, logos, or MP3 data are interchangedbetween friends or acquaintances. In line with the invention, the datatraffic in the “backbone” of the mobile radio communication network,such as in the GPRS backbone between an SGSN and a GGSN, is greatlyreduced in these cases. Whenever a data packet is provided with adestination address which is stored in the control network node'saddress register, this is identified by the inventive search function,and the invention now involves the data packet which is thus identifiedas relevant being handled and forwarded only by the control networknode. The invention thus avoids any bypass via a further network node.If the destination address is not present in the control network node'saddress register, the data packet is forwarded from the control networknode to a further network node in the network, such as to a GGSN in aGPRS network, which node is then responsible for routing the data packetto its destination address.

In one particularly preferred embodiment of the inventive method, theaddress register chosen is a “hashing table” with a hash function so asto be able to decide as quickly as possible whether an incoming IPpacket needs to be forwarded locally or via the GGSN. The hashing tablecomprises a list of entries containing only a binary value “1” or “0”.The organization criterion, i.e. the address in the table, is calculateddirectly using the hash function. This is done by converting the IPaddress into its 32 or 128 bit value, which can be used to access thetable directly. If the result of the test with the destination addressof an IP packet arriving at the SGSN is the value “1”, for example, thenthis signals the presence of a local destination, i.e. the communicationpartner is registered at the same SGSN as the sender of the IP packet,and in line with the invention the forwarding of the IP packet is thenhandled exclusively by the SGSN. If the result of the test is the value0”, then the IP packet needs to be routed via the GGSN. The table isupdated during the PDP context handling. To this end, whenever a contextis set up or canceled or modified, the IP address of the respectivesubscriber in the table is set to the respective value, that is to sayby way of example to “1” for “available locally” and “0” for “notavailable”.

Preferably, the mobile radio communication network chosen is a GPRS orUMTS network.

In addition, the present invention comprises a mobile radiocommunication network having at least one control network node, at whichmobile subscribers in the mobile radio communication network are managedon the basis of their current location and connections from/to acommunication terminal associated with a mobile subscriber managed atthe control network node are controlled within the mobile radiocommunication network, where the control network node contains a filterfunction which is used to filter incoming data packets on the basis of adestination address which is respectively indicated in the data packets.

Preferably, the control network node contains a table which records allsubscribers managed by the control network node with addressesappropriately associated with the subscribers. Using this table, thefilter function is preferably able to perform a comparison between adestination address indicated in a data packet and the table's recordedaddresses appropriately associated with the subscribers.

In one particularly preferred embodiment of the inventive mobile radiocommunication network, the control network node contains a routingfunction which can be used to route selected data packets with adestination address to this destination address by bypassing othernetwork nodes.

In one particularly preferred embodiment of the inventive mobile radiocommunication network, the control network node contains the filterfunction and the routing function coupled to one another such that thedata packets filtered out by the filter function on the basis of adestination address respectively indicated in the data packets can beforwarded to the respective destination address by the routing functionby bypassing other network nodes. This means that if the destinationaddress of a data packet arriving at the control network node iscontained in the address register of the control network node, and thisis accordingly identified by the control network node's filter function,then this data packet is routed to the destination address directly,bypassing other network nodes, such as a GGSN in a GPRS network, bymeans of the routing function provided at the control network node. Thisallows time and costs to be saved.

The invention thus provides support for “peer-to-peer services” or P2Pservices in a mobile radio communication network, too, in a similarmanner to the development on the Internet. Use of the invention allowsboth the operator and mobile radio subscribers who are managed by thecontrol network node to benefit from geographical proximity. For anoperator the result is a lower load on the network between the SGSN andGGSN, and for a mobile radio subscriber shorter latencies andaccordingly, lower charges.

Other advantages are demonstrated with reference to the figure below, inwhich

FIG. 1 shows a schematic illustration of an embodiment of the inventivemethod using the example of a GPRS network.

FIG. 1 shows an embodiment of the inventive method using the example ofGPRS network. From the GPRS network, the present example shows a radionetwork controller RNC-A, which is responsible for the network access ofa mobile radio subscriber A using his mobile communication terminal MSA, a control node SGSN, which on account of local proximity manages boththe mobile radio subscriber A with his mobile communication terminal MSA and a further mobile radio subscriber B who has his mobile terminal MSB close by, a GGSN, which in the present case provides both A and B witha central gateway for linking to a packet data network (called logicalreference point Gi in the standards), and a second radio networkcontroller RNC-B, which is responsible for the network access of thesubscriber B. A mobile radio subscriber A now wishes to use his mobilecommunication terminal MS A to set up a connection to a mobile radiosubscriber B or to his mobile communication terminal MS B and to use theconnection to send data packets. A data packet coming from A or comingfrom MS A contains a destination address, namely the address of thesubscriber B or of MS B in the case illustrated. It is now known (asindicated by the dashed line in FIG. 1) that the data packet is tunneledfrom MS A via the radio network controller RNC-A, the SGSN, to the GGSN.In the RNC-A, the data packet is encapsulated into an appropriate IPtunnel. This means that the data packet is handled transparently as faras the GGSN. Viewed logically, the data packet is not unpacked, i.e.decapsulated, until it is behind the GGSN, namely at the reference pointGi, and the destination address stored in the data packet is used toroute it from there to this very destination address. In the presentcase, this means that where the destination addressee, namely thesubscriber B, is situated at a location close to the subscriber A, thedata packet is now returned from the reference point Gi to the sameGGSN, is packed, i.e. encapsulated again there, and is routed from thereto the same SGSN managing both A and B. The SGSN then routes the datapacket to RNC-B and ultimately to MS B. In this case, the distancebetween SGSN and GGSN and between GGSN and, for example, an externalrouter which is connected to the reference point Gi, is respectivelycovered twice, which is not necessary for the desired operation, namelysending a data packet from A to B. In line with the invention, the SGSNnow has an address table, a search function and a routing function. Inthe table, each subscriber managed at the SGSN is allocated the IPaddress assigned to him during setup of a PDP context. The table is inthis case constructed such that the search function and the destinationaddress stored in the incoming data packet can be used to establish veryquickly whether or not the destination address is contained in thetable. If the destination address of subscriber B is contained in thetable, as is the case in the present example, then the search functionreads the interface identifier (denoting the physical link) of the RNC-Bhandling the subscriber B and the data packet is sent to the RNC-Bdirectly via this interface. By handling the data packets at theinterface to the radio access network, the GGSN is bypassed. In thisway, the SGSN's search and filter function assessing the destinationaddresses,

in conjunction with the address register or the table of all subscribersor their IP addresses managed by this SGSN at the respective time,allows optimized routing for the data packets which are to be sentbetween all of the subscribers managed by this SGSN at the respectivetime.

1. A method for controlling data interchange between mobile subscribersin a packet-oriented mobile communication network, comprising: managingeach subscriber at a particular control network node in the mobilecommunication network on the basis of his respective current location inthe mobile communication network, and controlling connections from/to amobile communication terminal associated with the mobile subscriberwithin the mobile communication network by the appropriate controlnetwork node, wherein the control network node stores an addressregister containing all of the addresses associated with the mobilesubscribers managed by the control network node, the control networknode takes incoming data packets and reads a destination addressassociated with the data packets, and uses a search function to comparesaid destination address with the address register, if the destinationaddress is present in the address register then the data packets arehandled and forwarded within the mobile communication networkexclusively by the control network node, and if the destination addressis absent from the address register then the data packets are routedfrom the control network node to a further network node in the mobilecommunication network for the purpose of further handling.
 2. The methodas claimed in claim 1, wherein the address register chosen is a “hashingtable” with a hash function.
 3. The method as claimed in claim 1,wherein the mobile radio communication network chosen is a GPRS or UMTSnetwork.
 4. A mobile radio communication network having at least onecontrol network node, at which mobile subscribers in the mobile radiocommunication network are managed on the basis of their current locationand connections from/to a communication terminal associated with amobile subscriber managed at the control network node are controlledwithin the mobile radio communication network, wherein the controlnetwork node contains a filter function which is used to filter incomingdata packets on the basis of a destination address which is respectivelyindicated in the data packets.
 5. The mobile radio communication networkas claimed in claim 4, wherein the control network node contains a tablewhich records all subscribers managed by the control network node withthe addresses appropriately associated with the subscribers.
 6. Themobile radio communication network as claimed in claim 5, wherein thefilter function is able to perform a comparison between a destinationaddress indicated in a data packet and the table's recorded addressesappropriately associated with the subscribers.
 7. The mobile radiocommunication network as claimed in claim 4, wherein the control networknode contains a routing function which can be used to route selecteddata packets with a destination address to the destination address bybypassing other network nodes.
 8. The mobile radio communication networkas claimed in claim 4, wherein the control network node contains thefilter function and the routing function coupled to one another suchthat the data packets filtered out by the filter function on the basisof a destination address respectively indicated in the data packets areforwarded to the respective destination address by the routing functionby bypassing other network nodes.